Abstract: A solar protection device includes slats of refractive material rotatable about a longitudinal axis, having an even, flat upper side and having on their lower side prisms arranged serially without gaps and running parallel to the longitudinal axis. In order to maintain the condition for retroreflection with variations of the sun's position, the angle of inclination to the horizontal of the slats must be readjusted from time to time, at least seasonably. For automatic adjustment thereof a light sensing arrangement of two light sensors arranged oppositely on both cathetal legs of one of the prisms whose hypotenuse is formed by the upper side of the rotatable slat. Control by a drive and associated electronics is undertaken and continued as long as solar rays impinge on one of the light sensors with intensity exceeding a predetermined illumination level.